How to use org.eclipse.che.api.workspace.server.event

 @Override
 public void onCascadeEvent(BeforeWorkspaceRemovedEvent event) throws Exception {
  signatureKeyDao.remove(event.getWorkspace().getId());
 }
}

@Transactional(rollbackOn = {RuntimeException.class, ServerException.class})
protected void doRemove(String id) throws ServerException {
 final EntityManager manager = managerProvider.get();
 final StackImpl stack = manager.find(StackImpl.class, id);
 if (stack != null) {
  eventService.publish(new BeforeStackRemovedEvent(new StackImpl(stack))).propagateException();
  manager.remove(stack);
  manager.flush();
 }
}

@Override
public void onCascadeEvent(BeforeStackRemovedEvent event) throws Exception {
 removeStackPermissions(event.getStack().getId(), PAGE_SIZE);
}

@Transactional(rollbackOn = {RuntimeException.class, ServerException.class})
protected Optional<WorkspaceImpl> doRemove(String id) throws ServerException {
 final WorkspaceImpl workspace = managerProvider.get().find(WorkspaceImpl.class, id);
 if (workspace == null) {
  return Optional.empty();
 }
 final EntityManager manager = managerProvider.get();
 eventService
   .publish(new BeforeWorkspaceRemovedEvent(new WorkspaceImpl(workspace)))
   .propagateException();
 manager.remove(workspace);
 manager.flush();
 return Optional.of(workspace);
}

@Transactional(rollbackOn = {RuntimeException.class, ApiException.class})
protected void doCreate(StackImpl stack) throws ConflictException, ServerException {
 if (stack.getWorkspaceConfig() != null) {
  stack.getWorkspaceConfig().getProjects().forEach(ProjectConfigImpl::prePersistAttributes);
 }
 EntityManager manager = managerProvider.get();
 manager.persist(stack);
 manager.flush();
 eventService.publish(new StackPersistedEvent(stack)).propagateException();
}

 @Override
 public void onEvent(RuntimeAbnormalStoppingEvent event) {
  RuntimeIdentity identity = event.getIdentity();
  String workspaceId = identity.getWorkspaceId();
  WorkspaceStatus previousStatus;
  try (Unlocker ignored = lockService.writeLock(workspaceId)) {
   previousStatus = statuses.replace(workspaceId, STOPPING);
  }
  if (previousStatus == null) {
   LOG.error(
     "Runtime '{}:{}:{}' became abnormally stopping but it was not considered as active before",
     workspaceId,
     identity.getEnvName(),
     identity.getOwnerId());
  }
  LOG.info(
    "Runtime '{}:{}:{}' is stopping abnormally. Reason: {}",
    workspaceId,
    identity.getEnvName(),
    identity.getOwnerId(),
    event.getReason());
  publishWorkspaceStatusEvent(
    workspaceId,
    STOPPING,
    previousStatus,
    "Workspace is going to be STOPPED. Reason: " + event.getReason());
 }
}

@Override
public void onEvent(RuntimeAbnormalStoppedEvent event) {
 RuntimeIdentity identity = event.getIdentity();
 String workspaceId = identity.getWorkspaceId();
   identity.getEnvName(),
   identity.getOwnerId(),
   event.getReason());
   STOPPED,
   previousStatus,
   "Workspace is stopped. Reason: " + event.getReason());
 setAbnormalStopAttributes(workspaceId, event.getReason());

@Override
public void onCascadeEvent(StackPersistedEvent event) throws Exception {
 final Subject subject = EnvironmentContext.getCurrent().getSubject();
 if (!subject.isAnonymous()) {
  permissionsManager.storePermission(
    new StackPermissionsImpl(
      subject.getUserId(), event.getStack().getId(), StackDomain.getActions()));
 }
}

@Transactional(rollbackOn = {RuntimeException.class, ServerException.class})
protected void doRemove(String id) throws ServerException {
 final EntityManager manager = managerProvider.get();
 final StackImpl stack = manager.find(StackImpl.class, id);
 if (stack != null) {
  eventService.publish(new BeforeStackRemovedEvent(new StackImpl(stack))).propagateException();
  manager.remove(stack);
  manager.flush();
 }
}

@Transactional(rollbackOn = {RuntimeException.class, ServerException.class})
protected Optional<WorkspaceImpl> doRemove(String id) throws ServerException {
 final WorkspaceImpl workspace = managerProvider.get().find(WorkspaceImpl.class, id);
 if (workspace == null) {
  return Optional.empty();
 }
 final EntityManager manager = managerProvider.get();
 eventService
   .publish(new BeforeWorkspaceRemovedEvent(new WorkspaceImpl(workspace)))
   .propagateException();
 manager.remove(workspace);
 manager.flush();
 return Optional.of(workspace);
}

@Transactional(rollbackOn = {RuntimeException.class, ApiException.class})
protected void doCreate(StackImpl stack) throws ConflictException, ServerException {
 if (stack.getWorkspaceConfig() != null) {
  stack.getWorkspaceConfig().getProjects().forEach(ProjectConfigImpl::prePersistAttributes);
 }
 EntityManager manager = managerProvider.get();
 manager.persist(stack);
 manager.flush();
 eventService.publish(new StackPersistedEvent(stack)).propagateException();
}

@Override
public void onCascadeEvent(BeforeWorkspaceRemovedEvent event) throws Exception {
 removeWorkers(event.getWorkspace().getId(), PAGE_SIZE);
}